1. Field of the Invention
This invention relates to a brakable wheel hub device, more particularly to a brakable wheel hub device adapted to be rotatably mounted on a wheel axle of a bicycle.
2. Description of the Related Art
U.S. Pat. No. 6,371,252 B1 discloses a bicycle disc brake hub that includes a hub axle, and a hub shell rotatably coupled to the hub axle, and having a brake rotor attachment portion formed at an end thereof. The attachment portion has an external splined surrounding surface and an internally threaded surrounding surface. A mounting boss has internal splines to engage the external splined surrounding surface, and an axially extending protrusion to engage a brake rotor to prevent relative rotation. A locking ring has an externally threaded surface to threadedly engage the internally threaded surrounding surface of the attachment portion so as to secure the brake rotor relative to the hub shell. However, due to the particular construction of the hub shell and the mounting boss, manufacturing costs are relatively high. Moreover, since the locking ring directly abuts against the brake rotor, loosening of the threaded engagement between the locking ring and the attachment portion may occur after prolonged use and may result in disengagement of the brake disk from the hub shell.